Chiral NNLOsat descriptions of nuclear multipole resonances within the random-phase approximation

We study nuclear multipole resonances in the framework of the random-phase approximation by using the chiral potential NNLO_sat. This potential includes two- and three-body terms that have been simultaneously optimized to low-energy nucleon-nucleon scattering data and selected nuclear structure data. Our main focuses have been the isoscalar monopole, isovector dipole, and isoscalar quadrupole resonances of the closed-shell nuclei, ⁴He, ^16,22,24O, and ^40,48Ca. These resonance modes have been widely observed in experiment. In addition, we use a renormalized chiral potential Vlow-k, based on the N³LO two-body potential by Entem and Machleidt [Phys. Rev. C 68, 041001 (2011)]. This introduces a dependency on the cutoff parameter used in the normalization procedure as reported in previous works by other groups. While NNLO_sat can reasonably reproduce observed multipole resonances, it is not possible to find a single cutoff parameter for the V_low-k potential that simultaneously describes the different types of resonance modes. The sensitivity to the cutoff parameter can be explained by missing induced three-body forces in the calculations. Our results for neutron-rich ^22,24O show a mixing nature of isoscalar and isovector resonances in the dipole channel at low energies. We predict that ²²O and ²⁴O have low-energy isoscalar quadrupole resonances at energies lower than 5 MeV.